Aircraft builders are becoming increasingly concerned with saving fuel. Studies have shown that it would be desirable to be able to move the aircraft on the ground while taxiing solely with the help of independent drive devices that may be hydraulic or electromechanical, each having a motor member suitable for driving one of the wheels of the aircraft so as to enable the aircraft to move without help from its engines.
The motors fitted to such independent drive devices should be as light as possible, and it is therefore tempting to use gearing between the motor and the wheel it is to drive, thereby making it possible to achieve a significant reduction in torque. Nevertheless, during certain stages, the wheel acts as a driver and can drive the motor of the independent drive device. This applies for example during takeoff or landing. Given the presence of the gearing, the motor can thus be caused to rotate at a high speed that is not compatible with the lifetime or the dimensions of the motor. It is therefore essential to use a coupling member between the motor and the wheel in order to able to disconnect the motor from the wheel during such stages.
The use of a friction coupling member appears to be relatively unsuitable given the high level of torque that needs to be transmitted and the lack of space available for housing such a member.
It is possible to use coupling members that involve obstacles, such as a dog clutch, for example, that enable high levels of torque to be transferred through a compact device. Nevertheless, engaging coupling requires the aircraft to be stationary so that the obstacles can be brought into register in order to interpenetrate without damage, and that represents a drawback under certain circumstances, in particular when the pilot can leave the landing runway without braking, and thus a fortiori without stopping.